Fire resistant asphalt roofing

ABSTRACT

A fire-resistant roof covering comprising a mineral wool felt base saturated with asphalt and containing 50-70 percent mineral wool, said base being coated with a composition consisting of about 49 percent asphalt, about 40 percent ground trap rock filler and about 11 percent asbestos.

United States Patent 11 1 Schroeder Aug. 7, 1973 [54] FIRE RESISTANT ASPHALT ROOFING 2,458,143 1/1949 Burns et a1 117 92 [75] Inventor: Schnleder, Wilmette ilgiijlgi /i321 i ly? 1. 117/126 GB [73] Assignee: United States Gypsum Company, OTHER PUBLICATIONS h Abraham, Asphalts & Allied Sciences, 3d Ed., 1929 [22] Filed: Mar. 3, 1971 5 2 Appl. No.: 120,747

Related U.S. Application Data Continuation of Ser No. 742,524, July 5, 1968, abandoned.

U.S. Cl ..117/126 R, 117/32, 117/137, 117/140 R, 117/168 Int. Cl. D06n 5/00, C() 9k 3/28 Field of Search 117/140 R, 92, 126 AB, 117/126 R, 126 GB, 136,168, 137

References Cited UNlTED STATES PATENTS 4/1931 Chamberlain 161/236 Primary Examiner-william D. Martin Assistant Examiner--William H. Schmidt Att0rney-George E. Verhage, John Kenneth Wise and Dana M. Schmidt [57] ABSTRACT 3 Claims, No Drawings RELATION TO COPENDING APPLICATIONS This application is a continuation application of my copending application Ser. No. 742,524 filed on July 5,

1968, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a fire-resistant asphalt base covering, more commonly referred to as asphalt shingles.

At the present time the conventional asphalt composition shingles and protective coverings have not been successful in meeting the rigid requirements of fire un-' SUMMARY OF THE INVENTION It is an object of this invention to improve the fire resistance of asphalt composition coverings, as shingles and the like, and at the same time retain and improve all the excellent qualities of waterproofness, selfsealing, workability, flexibility, weather resistance, ease of application, etc., that are naturally inherent in this excellent product.

It is another object to provide an improved coating composition which can be applied by the use of conventional equipment, and yet at the same time have fire-resistant properties.

It is therefore possible by following the teachings of this invention, as more fully described hereinbelow, to produce an improved fire resistant asphalt composition covering that will qualify for the class A fire rating label, and that can be used without any special underlying felt to obtain class A label rating. It is obvious that the'savings not only'in cost ofmaterials but in construction are a material advantage. Unlike prior art asphalt composition coverings this improved covering will'not separate or delaminate between the coatings and the saturated felt when it is exposed to high heat as normally encountered in conflagrations.

DESCRIPTION OF THE PREFERRED EMBODIMENT The fire resistant asphaltcomposition covering and the improved product of this invention is obtained by combining a special type of non-flowable coating composition with an improved mineral wool felt.

This combination of an improved non-flowable coating composition and the improved felt containing definite amounts of combustible and incombustible'fibrous matter, which on burning out forms a coherent, strong, reticulated ash structure to serve as a base for thecoating is very important and essentialto produce an improved asphalt composition covering characterized'by its ability to withstand the severe fire, flame, and fire brand conditions to qualify for a class 'A label rating. The coating composition'by itself or in combination with a conventional organic felt base will not qualify. Neither will the improved felt in combination witha conventional'coating qualify for class A rating. lt is, therefore, apparent that the two components are a true combination since neither of them alone or in combination with conventional roofing material components are able to withstand the rigors of tests to qualify for class A label rating.

For sake of simplicity and clarity and to further illustrate the principles underlying this invention, each of the components and the combination will now be described in greater detail, but it is not intended that the same shall be considered as limitations for obviously there are a number of adaptations, extensions, variations and permutations that can readily be considered as within the spirit of this invention as defined by the hereunto appended claims.

The coating composition of this invention has as its basic material a bituminous substance such as asphalt having a softening point of 2l8-227F. as determined by ASTM E28-58T and a penetration of l52l as determined by ASTM D5-6l. Incorporated with this thermo-plastic material are materials which stops the flow of the bitumen when they are subjected to heat and also form a crust during the process of burning. The preferred formula consists of 49 percent coating asphalt, 11 percent 7MS-l asbestos and 40 percent ground trap rock filler. The coating asphalt is heated to a molten state and the other ingredients are added thereto. The resultant mixture is readily applicable to the surface of the special type of asphalt saturated sheet which will be subsequently described and can be applied in much the same manner as any other coating using the conventional asphalt composition shingle machine, if desired.

After the coating is applied, regular mineral granules are sprinkled upon and rolled onto the surface in accordance with the usual practice.

The felt can be made with much the same type of equipmentnow used in the manufacture of ordinary rag roofing felt. However, about 50 percent by weight of the organic fiber commonly used in making the felt is replaced with mineral wool. The felt can be formed on a regular roofing felt machine, provided the mineral wool complies with certain desirable requirements described below.

The mineral wool fibers should have approximately a diameter between 2 and 8 microns and be substantially free from non-fibrous material such as slugs. The fibers should be fairly long and flexible and not easily etched by water. Not less than about 50 or more than about percent by weight of such mineral wool should be used. The remaining fibers are of organic nature and are substantially the same as those ordinarily used in making roofing felt such as corrugated waste, special mixed paper, or other cellulosic material.

The mineral wool, either as it is formed or before it is made into a felt, is treated to remove large beads and other impurities, preferably by passing it in a water suspension through a separating device. The mineral wool is then blended inproper proportions with the other constituents such as kraft, etc.,fibers, to form a felt on the standard paper making machine.

Felts made with mineral wool. in accordance with the disclosure of this invention will absorb more asphalt in ,proportion to organic material and absorb it more quickly than-the prior artorganic felt. Also, after the saturated felt has been subjected to a burnout, the ash .forms a strong and coherent reticulated-structure.

tained that readily passes all the requirements of class A label service as specified by the Underwriters Laboratories.

The method of testing and conditions for various class label requirements are fully described in a publication of the Underwriters Laboratories, dated September 1958, entitled Test Methods for Fire Resistance of Roof Covering Materials.

in order to obtain a class A, B, or C rating by the Underwriters Laboratory, the roof coverings when applied under certain conditions and tested by their procedure must pass the requirements known as flame exposure, spread of flame and burning brand. Class A requirements are most severe, and in general clay roof tile, asbestos-cement tile, and similar materials may qualify. Asbestos felt base roofing with conventional asphalt coating will not always qualify. Class B requirements are less severe, and Class C requirements are still lower.

Tests made in accordance with the specifications of the Underwriters Laboratories on asphalt roofing made following the principle of this invention indicated that the products passed the class A label requirement. This performance is outstanding in comparison with most prior art asphalt composition roofing, which does not meet even the class B label requirements. The shingles were made in accordance with the following example which is given for illustrative purposes only.

EXAMPLE A felt consisting of 50 percent mineral wool and 50 percent kraft corrugated fiber was made in accordance with the procedure described above and saturated with asphalt in an amount of 140 percent by weight of the felt. The asphalt saturant has a softening point of 145-l55F. and a penetration of 38-45 as determined by the ASTM methods previously mentioned for the coating asphalt. A coating composition in an amount of 24.9-28.9 lbs. per 100 sq. ft. and consisting of 49 percent asphalt having a softening point of 2l8-227F. and a penetration of -21, 1 1 percent 7MS-l asbestos and 40 percent, ground trap rock filler was applied to the saturated mineral wool felt and a thinner layer (8-l2 lbs. per 100 sq. ft.) of the coating was applied to the back of the felt. Mica was dusted on the thin coat ing on the back of the felt and standard No. l l mineral granules (30.7 lbs. per lOO sq. ft.) were sprinkled on the coating on the front surface in the usual way. The coated felt was then cut into shingles of the desired size and shape. Spots of an adhesive composition consisting of 86 percent asphalt, 4 percent asbestos, and 10 percent coumarone-indene resin were applied to the granule side lengthwise across the shingle at about the midpoint in accordance with the usual practice. A strip of silicone-treated paper was placed on the back of the shingle, in accordance with the usual practice. The resulting 220 lb. self-sealing asphalt shingle passed the flame exposure, spread of flame, and burning brand tests and was given a Class A rating by Underwriters Laboratories.

Talc may be substituted for the mica backing when making all white or pastel-colored shingles.

When making a 240 lb. shingle, the coating is increased to 28.3-32.3 lbs. per sq. ft., the back coating and granule weight and size remaining the same. For a 295 lb. shingle the top coating is increased to 32-36 lbs. per 100 sq. ft. and No. 8 or No. 9 granules are used in the amount of 50 lbs. per 100 sq. ft.

This highly improved asphalt composition shingle has great commercial utility since much greater fire protection can be obtained for roofs at little increase in cost. Asphalt composition roofing is not only economical but also under action of heat from the sun forms a selfsealing joint with the adhesive which is highly desirable.

The terms asphalt or'asphaltic material define a bituminous substance, substantially hard at room temperatures, and having plastic flow when heated and also having high weather resistance. It can be derived from petroleum or oil and is suitable for use in this invention, if it has the required softening point and penetration values.

What is claimed is:

1. In a fire-resistant asphalt roofing covering including a felt base and a coating composition applied thereto, said base comprising mineral wool, organic fibers, and saturating asphalt, said mineral wool forming about 50 to 70 percent of the combined weight of said wool and said fibers, said composition including asbestos and coating asphalt; the improvement comprising said asbestos being present in said composition in an amount which is about 1 1 percent by weight of the total composition, and said saturating asphalt being present in an amount such that the weight ratio of the same to the total weight of said wool and fibers is about 1.4 to l.

2.-The improved roofing covering as defined in claim 1, wherein said saturating asphalt has a softening point of about F to F. and a penetration of about 38 to 45 taken at 77F. in accordance with ASTM D5-6l.

3. The improved roofing covering as defined in claim 1, wherein said coating asphalt has a softening point of about 2l8-227F. and a penetration of about 15-21. a a a a e 

2. The improved roofing covering as defined in claim 1, wherein said saturating asphalt has a softening point of about 145*F to 155*F. and a penetration of about 38 to 45 taken at 77*F. in accordance with ASTM D5-61.
 3. The improved roofing covering as defined in claim 1, wherein said coating asphalt has a softening point of about 218*-227*F. and a penetration of about 15-21. 